Heretofore, in cultivation of crop plants in cropland, it has been desired to control weeds which inhibit the growth or the harvest of crop plants. Further, in non-cropland also, it is beneficial for utilization of the non-cropland to effectively control weeds. Thus, control of weeds is necessary in each of cropland and non-cropland, and various herbicides have been used. However, in recent years, there is a movement to reduce the dosage of a herbicidally active ingredient as far as possible, so as to reduce the environment load at a site where the herbicide is applied or the periphery thereof.
For example, blending of a nonionic surfactant with a spray solution is known to improve the herbicidal effect and to reduce the dosage of the herbicide, and an alkylaryl polyglycol ether type surfactant (tradename: Citowett, manufactured by BASF France) may be mentioned as a general purpose product. Further, EP0598515 discloses remarkable improvement of the herbicidal effect by blending of an ethoxylated fatty amine type surfactant with a vegetable oil and/or a mineral oil in application of nicosulfuron or primisulfuron as a specific herbicidal sulfonylurea compound.    Patent Document 1: EP0598515